Finding the Fourth Proportional to 1,388.62, 1,916.51 and 864.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.62 : 1,916.51 = 864.82 : x
2. Step 2: Convert to fraction form
   1,388.62/1,916.51 = 864.82/x
3. Step 3: Cross multiply
   1,388.62x = 1,916.51 × 864.82
4. Step 4: Simplify right side
   1,388.62x = 1,657,436.18
5. Step 5: Solve for x
   x = 1,657,436.18/1,388.62
6. Step 6: Final answer
   x = 1,193.59